Johnson counts the cost of the bruising defeat to Ireland

The England manager Martin Johnson is not yet surveying the debris of a failed Six Nations campaign, although it will break into a thousand pieces if his struggling side lose the Calcutta Cup match with Scotland in Edinburgh on Saturday week.

He did, however, spend yesterday casting a dark eye over the damage caused to his first-choice personnel during the painful defeat by Ireland at Twickenham.

Both the full-back Delon Armitage and the lock Simon Shaw are at risk of missing the rest of the tournament: the former with a nasty rib cartilage injury that may take six weeks to clear up; the latter with a mangled joint in his left shoulder. The full extent of Shaw's problem has yet to be ascertained, but two teams of medics – one from England, the other from Wasps – were due to meet today to discuss the results of a scan, together with the findings of a specialist's review.

Johnson immediately decided to hold back Armitage's like-for-like replacement, the Northampton full-back Ben Foden, and Shaw's engine room deputy, the Leicester lock Louis Deacon, for Murrayfield preparation instead of releasing them to their clubs for Premiership activity this weekend. David Wilson, the Bath prop, was also confined to barracks, as were those 13 members of Saturday's starting line-up still considered to be in one piece. The remainder of the elite squad, including one or two individuals challenging hard for promotion – the Leicester outside-half Toby Flood, the Wasps flanker Joe Worsley – were made available for the forthcoming round of league matches.

Armitage has been miles out of form since recovering from the dislocated shoulder that prevented his participation in the three Twickenham Tests before Christmas, and the 49 minutes he spent on the field against Ireland were a long way short of vintage. Foden, one of the sharpest attacking threats in Premiership rugby this season, would have pressed for a Calcutta Cup place even had his rival from London Irish survived Saturday's contest intact. Now, he is a hot bet for a first start at international level.

Deacon, the Leicester captain for long periods of the current campaign, is much more of a tried and tested figure, having been in the England mix since his debut against Samoa in 2005. One of the Midlanders' most effective forwards, he has rarely, if ever, scaled the heights in national colours. However, his scrummaging and mauling work against Ireland was of a sufficiently high standard to paper over the cracks left by Shaw's early departure. He has a good deal of support among the England hierarchy, most of whom have strong Leicester connections, and can expect another opportunity to answer those who suspect he is short of genuine Test class.

It is possible that Johnson will make further changes to his starting combination for what has become a must-win encounter with the Scots in Edinburgh – one of England's least favourite locations, a city where they have a damaging habit of losing by half a dozen points. Jonny Wilkinson's performance against the Irish left him exposed to renewed criticism while the back-row unit of James Haskell, Lewis Moody and Nick Easter finished a distant second to an inspired visiting threesome. There is a delicate judgement to be made, hence the heightened interest in this weekend's Premiership business.

Wales, beaten for a second time in three Six Nations outings last Friday night and effectively out of the running for the title, have lost players of their own. Two Cardiff Blues tight forwards, the lock Deiniol Jones and the hooker Gareth Williams, are off-limits for next week's meeting with Ireland in Dublin. Jones hurt his ribs early in the game against France at the Millennium Stadium while Williams, unavailable since picking up a knee problem against Scotland last month, has made insufficient progress to challenge for a place.

Warren Gatland, the Wales coach, has real problems in the second row, thanks to the injury absences of Alun Wyn Jones and Ian Evans and the need to play the multi-tasking Jonathan Thomas on the blind-side flank in place of Andrew Powell, ditched from the squad after his recent escapade with a golf buggy. Bradley Davies, Luke Charteris and Ian Gough are under consideration for the difficult trip to Croke Park. There is better news on the hooking front, though. The Lions Test forward Matthew Rees, badly missed during this championship, is fit to press for a return to action.

On the club front, Gloucester have resigned themselves to life without their All Black tight-head prop Greg Somerville until the back end of April. Somerville suffered a fracture in his left forearm during the comprehensive Premiership victory over Sale on Saturday and underwent plate-insertion surgery that night.

Ins and outs: Foden and Deacon prepare to fill injured men's boots

Ben Foden (Northampton)

Age: 24

Caps (as replacement): 2 (2)

Honours: European Challenge Cup, 2008-9

Season so far: Two Six Nations matches.*Likely to replace: Delon Armitage,(London Irish)

Likely to replace: Delon Armitage

Age: 26

Caps: 14

Honours: None.

Season so far: Three Six Nations matches.

*Louis Deacon, (Leicester)

Age: 29

Caps: 9 (7)

Honours: 4 Prem titles, 2 Heineken Cups, 1 Anglo-Welsh Cup

Season so far: Come on as replacement three times.

*Likely to replace: Simon Shaw, (Wasps)

Age: 36

Caps: 42 (16)

Honours: 4 Prem titles, 2 Heineken Cups, 3 Anglo-Welsh Cups

Season so far: Played in all three Six Nations matches.